Abstract
Ultrasound-guided protein delivery is promising for site-specific
control of cellular functions in the deep interior of the body in a
noninvasive manner. Herein, we propose a method for cytosolic protein
delivery based on ultrasound-guided intracellular vaporization of
perfluorocarbon nano-droplets. The nano-droplets were conjugated with
cargo proteins through a bio-reductively cleavable linker and introduced
into living cells via antibody-mediated binding to a cell-surface
receptor, which gets internalized through endocytosis. After the cells
were exposed to ultrasound for endosomal escape of proteins, the
ultrasound-responsive cytosolic release of a cargo enzyme was confirmed
by visualizing the hydrolysis of the fluorogenic substrate using
confocal microscopy. Moreover, a significant decrease in cell viability
was achieved via the release of a cytotoxic protein in response to
ultrasound treatment. The results of this study provide the proof of a
principle that protein-conjugated nano-droplets can be used as carriers
in ultrasound-guided cytosolic delivery of proteins.